Saliva, the product of salivary gland secretion, is essential for the maintenance of oral health. Control of salivary secretion is mediated by the autonomic nervous system, which influences the ion, water and protein transport properties of salivary cells. In order to further our understanding of the mechanisms involved in the regulation of salivary gland secretion, we have sought to establish and study clonal lines of salivary cells which possess neurotransmitter signal transduction mechanisms coupled to functional cellular responses. The use of established cell lines offers several advantages over acute in vitro preparations: (1) long term studies can be carried out, (2) studies can be carried out on specific types of cloned cell lines which possess the same genetic background, and (3) somatic cell genetic and molecular biological techniques and be utilized to investigate various regulatory mechanisms. During this reporting period we have characterized several functional neurotransmitter responses in established rat human salivary epithelial cell lines in culture, and we have isolated several mutant cell lines which might be defective in processes subject to neurotransmitter regulation.